# Non-Linear Control

• Wodek Gawronski
Part of the Mechanical Engineering Series book series (MES)

This chapter discusses three main sources of the antenna non-linear behavior: velocity and acceleration limits, dry friction, and backlash. The velocity and acceleration limits are neutralized by using the command preprocessor, or anti-windup technique. The friction model is presented and the dither is analyzed as a cure for the antenna sticking at low velocities. The backlash model is given and the performance of an antenna with applied counter-torque is analyzed.

## Velocity and Acceleration Limits

The antenna control system is shown in Fig. Besides the controller, it includes the acceleration and velocity limiters. The acceleration limiters are implemented because the motor currents must be limited to avoid overheating (the currents are proportional to the antenna acceleration). Antenna velocity is limited for safety reasons. Those limits are not affected during normal tracking, but are reached during slew operations. When the limits are reached, the antenna is in a non-linear...

## Keywords

Large Step Friction Torque Motor Torque Applied Torque Wheel Velocity
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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